In the related art, in an electronic apparatus, such as digital still cameras or digital video cameras, equipped with an image capture function, in one example, a solid-state image sensor such as charge-coupled device (CCD) or complementary metal-oxide-semiconductor (CMOS) image sensor has been used. The solid-state image sensor has a pixel in which a photodiode (PD) that performs photoelectric conversion and a plurality of transistors are combined, and an image is constructed on the basis of pixel signals that are output from a plurality of pixels arranged on an image plane on which an image of a photographic subject is formed.
Further, as the size of a pixel become smaller, there has been concern that a region enough to install a PD is very difficult to be prepared and the signal-to-noise (SN) ratio is decreased, and so techniques for increasing the volume of a PD have been developed.
In one example, a technique capable of preventing the decrease in saturated electric charge amount, sensitivity, or the like and of improving random noise, random telegraph signal (RTS) noise, or the like by separating a PD and a transistor in the depth direction has been developed (e.g., refer to Patent Literature 1).
Further, an imaging device including a multiplier sensor for multiplying electrons due to impact ionization by an electric field in order to further improve the sensitivity has been developed (e.g., refer to Patent Literature 2).